Hey Dmax, one more quick question.

[engineeradam]

if you dont remember my torque convertor wasn't working properly. I have concluded it is the tps. Its garbage, done, cooked.
So i hard wired it out, so that the tranny gets constant power unless the brake is depressed. I understand theres alotta of different wirings for inside the tranny. But should i have a switch? For towing or something? It shifts fine.

Its a 1/2 ton 4x4 6.2, 700R4 1987 all orig.

[DmaxMaverick]

It depends on what you want as an end-goal. On my 85, I originally bypassed all the grounding switches inside the tranny (except for the TCC solenoid). This gave me almost exclusive manual control of the TC. No matter what's done, or how it's driven, the TC will unlock, hydraulically, when the governor drops below speed (non electrical, the fluid pressure drops out below speed). The TC won't stay locked to a dead stop, causing a stall. The TC locks at about 28 MPH (about 10 MPH in 4 low) on acceleration (TV input required to supply fluid pressure). Initially, I left the brake switch in the loop, with a bypass toggle switch, and the main TC power supplied by a push/pull switch on the shift lever. It was really cool to mess with early on, but in the end, it is left in the "locked" position almost all the time. The only time I allow it to unlock is when descending a steep grade that's between the gears, to hold constant speed.

Removing the TPS from the loop reverts the system operation to previous model years (1985 didn't have one for TCC). The TPS is primarily for EGR operation (which, oddly enough, doesn't work on mine anyway), but the EPA decided at one time the TCC should also be controlled, for some obscure reason. They think you will use less fuel and create less emissions if the engine speed is allowed to drop lower when coasting (and the reason the brake switch is also in the loop). The reality is, when coasting on compression (inertia pushing the engine RPM above the governed idle speed), the fuel shuts off completely, cooling the exhaust output (no fuel being burned), and, of course, using NO fuel (as opposed to their assumption of less). With the TC open/unlocked, coasting at lower engine speeds causes the pump to keep the engine speed above the governed idle, burning fuel while you are trying to slow down, or maintain a speed on compression. Real rocket scientists, those guys. This may have some application in a passenger car, but not on a truck (for a number of reasons), IMO.

If your EGR is still functional, bypassing the TPS may cause some issues in that area. If it doesn't work, for whatever reason (we don't have to go there), carry on.

[engineeradam]

I removed all the emissions, i am now looking for a jcode intake to finish the process. speaking of removing useless stuff;

So your saying i can also remove the brake switch? And i should add a cut off for going down hills?
also what does the tcc effect when towing? Should it be locked or unlocked?

Btw. thanks alot your giving alot of usefull advice to a 19yr old kid who loves his diesel but is going off mostly gasser knowledge. and im sick off asking questions and people responding with 350 answers.

[john8662]

All 6.2's with a TH700R4 had a TPSwitch, starting in 1982. 1989-1993 they were TPSensors giving a voltage referance to the PCM to control EGR and TCC Lockup.

Personally, I'd return the engine/transmission configuration back to stock. Install a new TPS, adjust it.

If you re-wire the transmission internally you can get the TCC to stay locked right down to a stop and nearly kill the engine. A true manual way, but you can't forget to turn it off. This is if you pass the 2nd switch in the valve body with a jumper and leave just the solenoid in the loop. Just FYI...

The TPS is dual purpose, in that the two green wires on the top of the TPS are the only two wires that have anything to do with the TCC Lockup. There is actually a little switch and ball in that switch that clicks on and off depending on the wheel width inside the TPS. The other wires are all for the EGR.